WASHINGTON (WUSA) -- A four-year-old girl is in critical condition after an overnight house fire and one man is in police custody for what happened after firefighters arrived.

The fire happened at 3 a.m. Sunday in the 2600 block of 33rd Street Southeast.

Leon Harrison, a witness, said, "I saw the smoke coming out of the house. There was thick smoke. It was so thick it was covering the lights."

Flames were shooting out of the home where seven people lived, including a mother and her two small children.

Everyone got outside except the four-year-old little girl who had to be rescued.

John Jackson told us, "You could hear windows popping and a woman scream."

According to Lt. Christopher Kauffman of the Metropolitan Police Department, "The family takes a count outside and sees that the 4-year-old is missing. Firefighters find the four-year-old upstairs."

The little girl is in critical condition with burns and smoke inhalation.

When firefighters arrived, fire was seen coming from the basement and the first floor.

Metropolitan Police Lt. Christopher Kauffman says tensions were running high as firefighters battled the blaze. He says the landlord who also lived at the home got into a fight and threatened one of the women.

According to the police report, the 30-year-old man was arrested on felony assault and threatening to kill one of his tenants.

Investigators are also looking to see if the fire was intentionally set.

Police are still trying to figure out how the argument escalated and what caused the fire.

What neighbors and family are thinking about is the 4 year old little girl still in the hospital.

"It's just a terrible incident. Our prayers are with the family," said a neighbor.